Delayed coking is a process which in general provides a means whereby a petroleum fraction is heated to a temperature at which it will thermally decompose to provide a solid coke product and a hydrocarbon distillate product. Specifically, the process provides that a heavy petroleum fraction can be fed into a coking drum under conditions which prevent the petroleum fraction from vaporizing until it has partially decomposed. The decomposition process provides a petroleum distillate which is recovered from the coking drum and a heavy tar which continues to decompose until a porous coke is deposited as a mass within the drum.
In general practice delayed coking is accomplished by first distilling a liquid petroleum feed stock until the lighter ends have been recovered and a heavy residium remains. This heavy residium is thereafter heated and fed into a coking drum wherein it is subject to temperatures up to 1000.degree.F. to thereby effect decomposition of the petroleum to a vapor distillate product and a solid coke product. The petroleum distillate is recovered from the coke oven and a solid coarse coke remains within the drum. The vapors formed during the decomposition of the heavy residium produce pores and channels in the coke. Incoming oil from the furnace or the heater passes through these channels. Normally, fresh residium is fed to the coking drum until the drum is essentially filled with a mass of coke at which time the residium feed is discontinued and the coke is thereafter cooled and cut to be recovered.
When the coking drum is filled and feed material cut off, the coke is purged with steam to remove any remaining volatile components. After the steam purging, the coke is quenched with water to cool the coking drum and coke therein to a temperature below 200.degree.F. This quenching operation is provided in a controlled manner so as not to subject the coking oven to excessive steam pressure created when water is fed to the coke at temperatures in the range of 700.degree.F. to 900.degree.F. One of the problems encountered in the delayed coking process is the substantial amount of time normally required to quench the hot coke to a point where it can be removed from the drum. By the process of the present invention, it has been discovered that the quench time of the process can be reduced by utilizing the maximum safe feed rates of quenching water into the filled coke drum.